1. Field of the Invention
This invention relates to dispensing apparatus for dispensing insecticide material from a crop dusting aircraft.
2. Discussion of Related Art
A crop spraying or crop dusting aircraft carries a storage bin known as the "hopper" which is filled with the chemical to be sprayed by the aircraft. The hopper is generally a metal box which decreases in cross-sectional area from the top toward the bottom. The bottom of the hopper consists primarily of two doors which can be opened in an emergency to quickly dump the chemical in order to lighten the weight of the aircraft. The hopper doors can also be used in dispersing a payload such as dry fertilizer. Ordinarily, when the hopper is filled with a liquid, the liquid is pumped from the hopper through a small hole located about six inches above the bottom. When the level of the liquid reaches the level of the hole, no more chemical can be pumped from the hopper and the airplane returns to the landing field with approximately six inches of chemical left in the hopper. As long as the aerial applicator is using the same chemical, there is no harm or inconvenience associated with the inability to dispense the entire payload. However, in actual practice, a person in the crop spraying business may be spraying a rice crop with one chemical one day and a soybean or cotton crop with an entirely different chemical that is totally incompatible with the chemical used the previous day. It is not unusual to have the same aircraft used in spraying a variety of chemicals even in one day. Accordingly, it is necessary to remove the six inches of liquid chemical from the hopper each time the type of chemical is changed. One method of removing this remaining chemical fertilizer is by opening the doors in the bottom of the hopper and dumping the unused chemical. This dumping is not only wasteful of the chemical but is generally regarded as an unsafe operation since it deposits a large quantity of chemical on the ground in one place.
U.S. Pat. No. 2,404,812, issued July 30, 1946 to Rankin, shows a device for atomizing certain chemical and oils for the production of dry oil steam for signalling. The Rankin device includes a tank disposed in an aircraft. An outlet line is attached to the tank and terminates in a flexible end within the tank carrying a weight at its end portion to enable the open receiving mouth of the flexible pipe end to always seek by gravity the lowest point in the tank.
U.S. Pat. No. 3,860,202, issued Jan. 14, 1975, to Johnson, shows an apparatus for dispensing powdered granular insecticide material. The Johnson apparatus includes a storage hopper having downwardly converging walls terminating in a relatively small removal zone. An elevator conveyor taking the form of an auger has its lower end disposed within the removal zone of the storage hopper and inclines upwardly to an upper discharge location within the hopper where insecticide material positively removed from the removal zone of the storage hopper is deposited onto a filter screen across the top of a feed hopper.